Inflammation that prevents blood vessels from dilating properly could be the link between type 2 diabetes and heart disease, researchers report today in The Journal of the American Medical Association.

If more research confirms these findings, lead researcher JoAnn Manson says, blood tests to detect markers for inflammation might help screen people at risk for type 2 diabetes. Cholesterol-lowering statins and blood pressure drugs called ACE-inhibitors also might be useful, she says. "If medications can decrease this vascular inflammation and lower the risk of developing type 2 diabetes, that's a new avenue for treatment."

Manson, chief of preventive medicine at Brigham and Women's Hospital in Boston, and colleagues examined data on blood samples from 32,826 women as part of the ongoing Nurses Health Study. By 2000, 737 of the women, most of them in their 50s and 60s, had developed type 2 diabetes, the most common form of the disease. They were compared with 785 women of similar ages and races who did not develop diabetes.

Researchers looked for markers in the blood that indicate vascular inflammation and found that women with high levels of these substances were five times as likely to develop type 2 diabetes, even when other risk factors, such as obesity, inactivity and a family history of diabetes, were factored in.

Inflammation in blood vessels might slow the passage of insulin to the liver, muscles and other tissues, Manson says, and also could interfere with insulin's effectiveness in lowering blood-sugar levels. More than 18 million Americans have diabetes, which results from the body's inability to produce enough insulin or use it effectively.

Such inflammation in blood vessels is known to increase the risk of heart disease and stroke, Manson says, and "could explain the association between cardiovascular disease and diabetes." Cardiovascular disease is the leading cause of death in people with diabetes.